Recently, various functions, such as Radio Frequency Identification (RFID), Near Field Communication (NFC), Wireless Power Transfer (WPT) and an interactive pen tablet function, have been added to potable terminals, including mobile phones, tablet PCs and the like.
NFC is a technology to transmit data between terminals at a close distance of 10 cm in which a non-contact type short-range wireless communication module using a 13.56 Mz frequency band is used as one of RFID tags. NFC is widely used not only for mobile payment but also for transfer of information regarding goods and travel information for visitors, transportation, access control locks in supermarkets or shops by file transfer method.
In addition, ‘Android Beam,’ included in the smart phone system recently announced by Google, has an NFC-based short range information transmission and reception function to supports the transfer of data regarding photos, business cards, files, maps, and websites from one phone to another, as well as mobile payments.
A portable terminal is provided with a wireless charging function for wirelessly charging a built-in battery. Such wireless charging is performed by a wireless power receiving module built in a portable terminal and a wireless power transmitting module supplying power to the wireless power receiving module.
In addition, the wireless charging may be categorized as a magnetic induction method and a self-resonance method, and may be categorized as a PMA type and a Qi type depending on the method of detecting an access of wireless power receiving module to wireless power transmitting module.
At least one of the wireless power transmitting module and the wireless power receiving module is provided with a heat dissipating member outwardly discharging heat generated during wireless charging to increase the charging efficiency.
For example, graphite having a high thermal conductivity is usually used as a heat dissipating member. However, graphite has the following problems.
The graphite is excellent in heat dissipating effect since graphite is a high thermal conductivity material. However, graphite provides low charging efficiency, since severe eddy currents occur due to low resistance and the like. Therefore, there is a demand for a method able to improve charging efficiency while providing a superior heat dissipation effect.